User interface system and method for traversing a database

ABSTRACT

A user interface system and method for traversing a database. In one aspect the present invention includes providing a plurality of command options, each of the command options represented by a set of descriptive option index terms characterizing that command option. The set of descriptive option index terms characterizing the command options selected by a user, are compared with sets of document index terms. Each set of document index terms being compared characterizes an electronic document in a hypertext-type database which is selectively linked in that database with the user&#39;s present position. The comparisons result in a ranked list of the selectively linked electronic documents. The electronic documents are ranked in accordance with the relevancy of each document with respect to the selected command option. In another aspect of the invention, a plurality of command options are generated and displayed on a computer controlled display system (CCDS), each command option being represented by a portrayed character or personality associable to the user as being biased toward a particular type of information. Each of the command options represent a set of option index terms which characterize that particular command option. The set of option index terms characterizing the command option presently selected are compared with sets of document index terms. Each set of document index terms characterize an electronic document located within the database. The comparisons result in a ranked list of electronic documents, the documents being ranked in accordance with the particular bias of the portrayed character or personality.

This is a continuation of application, Ser. No. 07/316,331, filed Feb.27, 1989, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to user interfaces for data storage andretrieval systems and more particularly to a system and method forchoosing and executing queries to such data storage and retrievalsystems and traversing databases associated therewith.

2. Description of Related Art

Many current data storage and retrieval systems are organized using aprinciple commonly identified as "hypertext". Hypertext has resulted ascomputer work stations and digital storage have grown cheaper, morepowerful and more available. It has become increasingly more attractiveto extend the traditional notion of "flat" text files organizedhierarchically by allowing more complex nonlinear organizations ofmaterial. In a hypertext system, each data entity, i.e. document ornode, may be directly connected to other documents in the system bypointers, or links. The human user of a hypertext system moves between(browses) documents by following these links.

An essential characteristic of a hypertext database system is a machinesupported ability to efficiently traverse via these links from node tonode. In this regard, as noted in the article entitled "Hypertext: AnIntroduction and Survey" by J. Conklin, COMPUTER, September 1987, pages17-41, to qualify as hypertext, a system should require no more than acouple of keystrokes (or mouse movements) from the user to follow asingle link. The links provided by the interface transport the userquickly and easily to a new place in the hypertext system. Anothercharacteristic of a hypertext system is the speed with which the systemresponds to referencing requests. Only brief delays typically occur (oneor two seconds at most).

Although hypertext systems presently provide the ability for the user totraverse efficiently between nodes via links once he or she determinesthe desired links to be utilized, the number of documents in a hypertextsystem may be very large. Consequently, the number of links connected toany document may also become very large. This leads to difficulties in"navigating" through the database, the large number of links from eachdocument often resulting in confusion by the user when attempting toselect which link to follow.

One attempt to overcome this problem is by providing an overview displayor "map" of the hypertext documents and links. This technique has thedisadvantage of creating a large and complex map display when the numberof documents and links is large. There is a resultant need for furthercontrol and display options which the user must learn, and in theexpenditure of the user's time in manipulating the map, rather than moreeffective use of his time, such as reading documents.

Another solution to this navigational dilemma is to apply standarddatabase search and query techniques for locating documents which theuser is seeking. This involves addressing entities by content; that is,by text or numbers stored, in addition to or rather than a user-assignedname or symbol. This is usually executed by applying some combination,using boolean operations of key word and full string search andpredicates on other attributes (such as author, time of creation, type,etc.) of nodes or links. Various standard and proprietary languagesexist for querying structured databases or text retrieval systems (forexample, DIALOG, SQL). All of these languages share the drawback ofbeing arbitrary and complex, which poses a problem in applications whereuntrained users must query a data storage system, or in educational andtraining uses where presuming prior user training in the query method isinappropriate.

Experience with textual query methods has also shown that they aresubject to tradeoffs between precision (the number of retrieved entitieswhich are actually interesting) and recall (the fraction of totalinteresting entities which are actually found). Such studies have foundthat, for instance, a typical query to a legal information systemproduces only 20% of those database entities which are actuallyrelevant. (See the article entitled "An Evaluation of RetrievalEffectiveness for a Full Text Document Retrieval System", by D. C. Blairand M. E. Maron, COMMUNICATIONS OF THE ACM, March 1985, Vol. 28, No. 3,Pgs. 289-299.)

Other attempts to control the complexity of linking have concentrated ondatabase-wide elision of sets of links. For instance, the Intermediasystem allows the separation of links into sets called webs. Only one ofthese sets is visible to the user at a time. This achievessimplification but at the expense of possibly removing valuable linksfrom consideration if those links are stored in the webs which are notloaded. (See the article entitled "Intermedia: The Concept and theConstruction of a Seamless Information Environment", by N. Yankelovich,et.al., COMPUTER, January 1988, pgs. 81-96.)

Another approach to elision is filtering, that is, database-wideselection of documents and links based on a query, in a fashion similarto that described above. In some systems (e.g. see the article entitled"Super Book: An automatic tool for information exploration--hypertext?",by J. R. Remde, et al., Bell Communications Research, HYPERTEXT '87PAPERS, November 1987, pgs. 175-188; and the article entitled "Searchingfor Information in a Hypertext Medical Handbook", COMMUNICATIONS 0F THEACM, July 1988, pgs. 880-886), the pattern of links is also consideredin the decision to remove entities from the user's view. However,because such filtering methods treat the entire database at once, theyshare the limit of precision--recall tradeoff as described above,meaning that they achieve reduction of complexity at the expense of lossof information.

With the growing use of multimedia databases containing not only textualdocuments, but also data entities containing sound and graphics, and thegrowing utilization of hypertext-type nodal networks within thesemultimedia databases, the requirement for effective and meaningfulnavigation has become even more imperative.

Utilization of a hypertext-type nodal network in conjunction with amultimedia database may be described as a "hypermedia database". Thus,as defined broadly herein, the term "hypermedia system" refers to adatabase which may be constructed to include documents or nodes andmachine supported selected linkages or pointers which provide the userwith the ability to efficiently travel from one node to another. Thesenodes may include text, sound, or graphic material. An example of asystem that supports hypermedia is Apple Computer Inc.'s system soldunder the trademark "HYPERCARD" which allows traversal through ahypertext-type nodal network containing text, sound and graphics.HYPERCARD provides the machine supported ability to selectively traversein an automatic fashion via linkages, from one item to another, theitems being selectively linked to each other in the nodal network.

In attempting to develop improved techniques for browsing through matureHYPERCARD databases, the present inventors have discovered the novelsystem and method of the present invention. As will be disclosed below,an aspect of the present invention involves a process for selecting,ordering and displaying a subset of the possible links from a document,resulting in reduced user confusion while browsing through a hypermediasystem. Another aspect of the inventive technique involves the use of anintuitive representation to the user of options or "guides", theselection thereof effectively masking a complex indexing and querymethod.

SUMMARY OF THE INVENTION

A user interface system and method for traversing a database. In oneaspect the present invention includes providing a plurality of commandoptions, each of the command options represented by a set of descriptiveoption index terms characterizing that command option. Means areprovided for comparing the set of option index terms of the commandoptions selected by the user with sets of document index terms. Each setof document index terms being compared characterizes an electronicdocument in a hypertext-type database which is selectively linked inthat database with the user's present position The term "hypertext-typedatabase", as used herein, may refer to either a hypertext database or ahypermedia database. The comparisons result in a ranked list of theselectively linked electronic documents. The electronic documents areranked in accordance with the relevancy of each document with respect tothe selected command option. The user is therefore enabled toefficiently retrieve relevant documents in accordance with his selectedcommand option.

In another aspect of the present invention, a plurality of commandoptions are generated and displayed on a CCDS, each command option beingrepresented by a portrayed character or personality associable to theuser as being biased toward a particular type of information. Each ofthe command options represent a set of option index terms whichcharacterize that particular command option. Means are provided forcomparing the set of option index terms characterizing the commandoption presently selected with sets of document index terms. Each set ofdocument index terms characterize an electronic document located withinthe database. The comparisons result in a ranked list of electronicdocuments, the documents being ranked in accordance with the particularbias of the portrayed character or personality.

In a hypertext-type database the use of such portrayed character isparticularly useful, the portrayed character effectively serving as a"guide" to the user, the guide providing an efficient mechanism forbrowsing the database.

The automatic formulation of a ranked list of electronic documents maybe produced by assigning a match value to each electronic document beingcompared with the selected option.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates the computer incorporating the present invention.

FIG. 2 is a system diagram of the logic associated with the operation ofthe database traversal system of the present invention.

FIG. 3 is a schematic illustration of a simplified hypertext database.

FIG. 4 is a schematic illustration of the hypertext database of FIG. 3tagged with document index terms.

FIGS. 5a-5f are screen displays of a reduction to practice of thepresent invention.

FIG. 5a shows a screen display illustrating the choices of guides oroptions available for traversing the subject hypermedia database.

FIG. 5b illustrates a screen display with a window showing theparticular selected guide's option index terms and first choice ofarticle.

FIG. 5c illustrates a screen display of the selected electronicdocument.

FIG. 5d is a screen display with a window showing a ranked list ofpreferred documents.

FIG. 5e is a screen display with a window illustrating thecorrespondence between the presently selected document index terms andthe index terms characterizing the selected option.

FIG. 5f is a screen display with two windows, the top window showing thecorrespondence between the document index terms of another document onthe ranked list of documents and the option index terms characterizingthe selected guide.

The same elements or parts throughout the figures of the drawings aredesignated by the same reference characters, while equivalent elementsbear a prime designation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following detailed description is divided into several sections. Thefirst of these discloses a general system arrangement for storing,retrieving, and manipulating data. Subsequent sections deal with thetraversal system including construction of the database, specificationof the criteria set, user start-up, traversing the database, and the useof a guide in the user interface. Additionally, an example of animplementation of this system is provided.

I. General System Configuration

FIG. 1 illustrates a typical computer controlled display system (CCDS)implementing the present invention. Shown there is a computer 20 whichcomprises three major components. The first of these is the input/output(I/O) circuit 22 which is used to communicate information inappropriately structured form to and from the other parts of computer20. Also shown as part of computer 20 is the central processing unit(CPU) 24 and memory 26. These latter two elements are those typicallyfound in most general purpose computers and almost all special purposecomputers. In fact, the several elements contained within computer 20are intended to be representative of this broad category of dataprocessors. Particular examples of suitable data processors to fill therole of computer 20 include machines manufactured by Apple Computer,Inc., and International Business Machines (IBM). Other computers havinglike capabilities may be adapted in a straight forward manner to performthe several functions described below.

Also shown in FIG. 1 is an input device 30 shown in a typical embodimentas a keyboard. It should be understood, however, that the input devicemay actually be a card reader, magnetic or paper tape reader, or otherwell known input device (including, of course, another computer). Alsoshown is an audio input device 31 which converts analog audioinformation to digital information. The audio signal may be supplied bya microphone or other conventional audio source such as compact disc,cassette, etc. A mass memory device 32 coupled to the I/O circuit 22provides additional storage capability for the computer 20. The massmemory 32 may include other programs and the like and may take the formof a magnetic or paper tape reader, hard disk drive, compact laser disk,or other well known mass storage device. It will be appreciated that thedata retained within mass memory 32, may in appropriate cases, beincorporated in standard fashion into computer 20 as part of the memory26.

In addition, a "mouse" input device 34 is illustrated which permits theuser to input graphic information to computer 20 through I/O circuit 22,in a well known manner. Generally, mouse 34 provides cursor control toidentify and position a cursor on a display screen. A computercontrolled display monitor 36 is illustrated which is used to displaythe images being generated by the present invention. Such a displaymonitor 36 may take the form of a cathode ray tube (CRT), liquid crystalpanel (LCD), or other well known display devices.

An audio output analog signal converts digital information to analogaudio signals. The audio output is represented by numeral designation37. The analog output may be delivered to headphones, loudspeaker, orother well known audio mixing and storage devices such as magnetic tape.

In the present invention, memory 26 includes a "bit map" whichrepresents the video memory for display monitor 36. Each bit (or groupsof bits) in the bit map 40 within memory 26 corresponds to a displayelement on display monitor 36. Thus, the bit map can be described by atwo dimensional array of points having known X, Y coordinates. Thedisplay elements comprising the display of display monitor 36 may beselectively enabled, or disabled, as a function of the bit map of memory26 is "on" or "off". The use of bit maps to display images on a displaymonitor is well known, and will not be further described in detail inthis Specification.

II. The Database Traversal System

FIG. 2 is a diagram illustrating the logic associated with the operationof the database traversal system. The system diagram includes aplurality of data stores, designated generally as 40,40', 40" . . .which are shown to appear as three-dimensional depositories. The datastores represent collections of related data that can be stored in thecomputer mass memory or main memory. The system diagram also includes aplurality of process blocks, designated generally as 42, 42', 42" . . ., and shown to appear as rectangles. The process blocks 42 representinteractions between the user and the computer or interactions withinthe computer itself. It is assumed that the necessary program functionsare provided by the aforementioned operating system to displaycharacters and the like on the screen associated with the display device36.

A. Construction of the Database

The first data store in the system diagram is labeled "Hypertextdatabase". As noted, one aspect of the invention involves theutilization of any hypertext-type database. This may include hypermediadatabases, which include graphics and sound. However, for ease inexplanation, the system will be described in connection with a hypertextdatabase. In view of the noted broader utility of the invention, it willbe understood that this described application involving a hypertextdatabase is purely illustrative and not limiting in nature.

Referring to FIG. 3, a simplified schematic of a hypertext database isillustrated, designated generally as 40. (The corresponding hypertextdatabase is Data Store 1, also designated 40 in FIG. 2.) The database 40may be located on a hard disk or optical disk in mass memory 32 ormemory 26. Database 40 includes a plurality of hypertext nodes,designated Document A through Document E. The nodes may include text.(In a multimedia database each node might include, for example,graphics, a collection of sounds, or a combination thereof.) Althoughdatabase 40 includes only five nodes, for simplified illustrativepurposes, a typical hypertext database would include many more nodes.The nodes in the hypertext database 40 are linked by pointers or links,designated by the arrows in the figure. These links represent a machinesupported capability of a user to traverse from one node to another, asindicated by the arrows, in an efficient manner. As noted in theBackground of the Invention, transport should require no more than acouple of keystrokes (or mouse movements) and with only brief delays.

Links have two ends, and are usually considered to be directed, althoughit is common to support going "backwards" along the link. Theorigination of the link is called the "link source", and usually acts asa reference. The source can logically be either a single point or aregion of text. The other end of the link, the "destination" of thelink, usually functions as the reference, and can also be either a pointor a region. A region source (or destination) is a set of contiguouscharacters which is displayed in some way as being a single unit.

In forming a useful indexed hypertext database, the documents of thedatabase are tagged with descriptive terms or document index terms. Thedocument index terms may be drawn from a pool of possible index terms.Data Store 2, containing these index terms (i.e. Index Term Set), isdesignated 40' in FIG. 2. This set might, for example, be stored in themass storage 32 of the CCDS.

The Index Term Set may be formed manually (Process Block 3), orautomatically (Process Block 4).

In manual indexing, a human generates a set of indexing terms based onknowledge of the database's subject area. This may be unordered, or itmay be ordered in some fashion. A typical ordering is hierarchical, withmore specific terms nested in an outline fashion below general terms.

In automatic indexing, a computer uses an algorithmic process to extractindexing terms from the nodes of the Hypertext database. A typicalprocess, applied to text, is to extract every word from the documentcorresponding to the node, discard common or "stop" words and removecommon suffixes. The entire residue list of unique words are then in theindexing set for the database.

Terms from Index Term Set may then be applied to each of the nodes inthe hypertext database, by, for example, an automatic function of theCPU, in an algorithmic fashion or manually by the human editor. Thisprocess is represented as Process Block 5.

The resulting Indexed hypertext database (Data Store 6) is the same asthat designated as Data Store 1; however, it includes document indexterms. FIG. 4 illustrates this indexed hypertext database, generallydesignated 40". Thus, for example, as shown in FIG. 4, Document A mightbe tagged with Index Terms 1-4, Document B tagged with Index Terms 1, 5and 3, etc..

B. Specification of the Criteria Set

Typically, from the set of indexing terms, one or more criteria oroptions are formulated manually, by the author of the database or by anend user. This procedure corresponds to Process Block 7 in FIG. 2.Traversal from one node of the hypertext link to a second node, usingthe system of the present invention, requires that at least one indexterm included in a selected criterion be from the subset of index termscontained in the indexed hypertext database (as explained below).

The formulation of a set of index terms as a criteria or "option"correlates to forming a query in a normal retrieval system. Relevantindex terms for a particular criterion or option can be selected. Thus,for example, for one particular study, relevant index terms might beIndex Term 4 and Index Term 5. For another study, for example, to studya different viewpoint, a different set of index terms would be includedin another criterion corresponding to another option. A set of criteriaor options based on index term sets is illustrated as Data Store 8.

Preferably, this aspect of the invention utilizes a portrayed characteror personality to represent a complex set of index terms. In thisrespect, as will be described in detail below, this portrayed characterserves as a type of "guide" for the user in browsing through thedatabase, the guide representing a certain "viewpoint". As noted in theBackground of the Invention, it is difficult to traverse through amature hypertext database with a multiplicity of nodes and linkages.Applicants have discovered that confusion during the traversal of thedatabase can be greatly eased by use of such a guide.

As used herein the term "option index term" refers to an index termincluded in the set of index terms representing an option. The term"document index term" refers to an index term included in the set ofindex terms representing a document.

C. User Traversal

Now that both:

(1) a set of criteria or options based upon a set of option index termswhich contain (at least in part) a subset of the option terms in DataStore 8, and

(2) an indexed hypertext database (e.g. Data Store 6) have beenestablished, the system is set up to allow the user to traverse from onenode to a second node in the database. The user selects a first commandoption from the CCDS, as denoted by Process Block 9. Data store 10represents the selected option with selected option index terms taggedthereon.

The user, in browsing the indexed hypertext database, arrives at aparticular node in the database (see Process Block 11). This particularnode is represented by Data Store 12. The CPU computes the set of nodesconnected to this particular node by hypertext links (Process Block 13).The set of these linked nodes is represented in Data Store 14. Thedocument index terms characterizing the linked nodes are then comparedwith the option index terms characterizing the selected option. Thecomparison involves estimating the "relevance" of each linked node tothe selected option and is preferably an automatic, algorithmic process.The desired result is the assignment of a "match value" to each linkeddocument, the match value reflecting the correspondence between thedocument index terms characterizing that particular linked document withthe option index terms characterizing the selected option.

A preferred method for assigning matched values to linked documentsincludes utilization of the following equation:

    MV.sub.d =(i.sub.od).sup.2 /i.sub.o ×i.sub.d         (1)

where,

MV_(d) =the match value of a document, d;

i_(o) =the number of option index terms characterizing that particularoption;

i_(d) =the number of document index terms characterizing the documentfor which a match value is being determined; and,

i_(od) =the number of co-occurring index terms when comparing thedocument index terms of document d, for which a matched value is beingdetermined and the option index terms characterizing that particularoption.

Thus, by computation of a match value for each linked document, thelinked documents may be ranked in accordance with their relevancy to theselected option. This ranked list of documents is represented by DataStore 16. Thus, each specific option has a one-to-one correspondencewith a ranked list of documents.

For example, referring to FIG. 4, assume that the user is positioned atDocument A. Also, assume that the user selects an option which is taggedwith Index Terms 2 and 3. Therefore, matched values for each documentcan be computed as follows;

    MV.sub.B =(i.sub.oB).sup.2 /(i.sub.o ×i.sub.B)=1.sup.2 /2×3=1/6

    MV.sub.C =(i.sub.oC).sup.2 /(i.sub.o ×i.sub.C)=1.sup.2 /2×2=1/4

    MV.sub.D =(i.sub.oD).sup.2 /(i.sub.o ×i.sub.D)=2.sup.2 /2×3=2/3

Thus, the ranked list of linked documents sorted in accordance with therelevancy of each document with respect to the criterion set (i.e.option) comprising option index terms 2 and 3 is: D,C,B, in that order.

The above example is obviously a simplified illustration; however, theutility of this technique with reference to a complicated database isevident. Note that since each linked document had at least one documentindex term which was also in the set of option index terms, all threelinked documents had a match value. However, in the event that there isno correspondence, the match value would be zero and the document absentfrom the list of sorted documents. It is also pointed out that sinceDocument E is not directly linked to Document A, it is not evenconsidered for the ranked list of documents.

Furthermore, depending on the structure of the database and the specificfunctions to be provided, the list may be constructed, to not onlyexclude documents with match values of zero as described above; but,also to exclude documents having less than a predetermined cutoff value.

Data Store 16 represents a ranked list of documents. The user can thenpick from the displayed list of documents by selecting a command optionon the CCDS. Thus, traversal in the database from one node to a secondnode is accomplished by a process of selecting, ordering, and displayinga subset of possible links from a document, resulting in reduced userconfusion while browsing through the database.

This aspect of the present invention is an aid to the navigation problemin hypertext-type databases because it provides an automatic method forreducing and ordering the choice of links which may be traversed from aparticular node while browsing a hypertext.

Unlike the strategy of total elision of some classes of links, typifiedby the webs method described in The Background of the Invention, thepresent invention leaves all links intact for potential use by eitherthe user or the criterion evaluation process.

Furthermore, by restricting the operation of the criterion or query tothe scope of a single node's links, the present invention largely avoidsthe precision/recall tradeoffs typical of information retrieval. Thesetradeoffs are produced as users attempt to reduce the number of itemsresulting from a query to a managable number. Because the present methodbegins with a smaller set, i.e., only those nodes linked to thecurrently visible node, this tradeoff is largely ameliorated.

The precise manner in which a document is selected is a matter of designor user preference. For example, an extremely expedient "tour" throughthe database using a specific option representing a set of option indexterms may be conducted by eliminating any display of the ranked list ofdocuments, the selection of a command resulting in automaticrepositioning of the user to a position in the database which representsthe document which is first on the ranked list. Or, the display ofrelevant documents might be limited to a specific number, for example,the first four or five documents on the ranked list.

The set of criteria (options) may be predetermined by the systemdesigner or may be created by the end user. In the second case the enduser would develop his or her own option index terms, the set of optionindex terms being added to the set of criteria (Data Store 8).

III. Use of a Guide as the User Interface

As noted, one aspect of the invention is the use of guides as optionswhich are represented to the user on the computer display in the form ofa portrayed character or personality. The guides may be displayed to theuser as a pictorial representation, with or without accompanying text,sound or video. Applicants have discovered that the use of such acharacter or personality can draw associations in the mind of a userthat are extremely strong yet representable by a complex set of indexterms. For the end user to attempt to formulate such a complex set ofindex terms would be extremely inefficient. Furthermore, applicants havediscovered that utilization of such a guide with a hypertext-typedatabase can provide a very powerful tool for traversing the database.

For example, consider a database consisting of documents relating to theCivil War. Use of this traversal system in combination with thehypertext-type database allows the user to be guided through thedatabase through, for example, the viewpoint of a slave, or for example,through the viewpoint of a confederate soldier.

One of the expectations aroused by the human image is personality.Personality is a way of explaining the complex set of motivations andreasoning that any person exhibits. It allows one to form a predictivemodel of a person's behavior and response without knowing minutae oflife experience and aspirations. Similarly, in representing a complexset of behavior patterns in the computer, as created by an informationquery, a human portrayal is useful when the user cannot or does not wantto know the actual mechanism which is being invoked. The anthropomorphicrepresentation engages the user's expectation of personality, i.e., acomplex but predictable pattern of action. It solves the problem ofcomplex query languages by providing a more limited repetoire ofstereotypic, personality represented choices.

For the end user to create a set of option index terms which wouldeffectively guide him through the database with the viewpoint desiredwould be exceedingly difficult and time consuming. However, professionaltext editors have the capability of providing meaningful sets of suchindex terms. This tool is even more powerful when utilized with ahypermedia database. Obviously, creating meaningful queries for use witha database containing electronic documents consisting of graphics orsounds is even more difficult than creating such queries for a databasemerely containing text.

IV. EXAMPLE

As noted, the present applicants, utilizing the principles of thepresent invention, have created a user interface for a database composedof multimedia material. The vehicle for delivery is HYPERCARD. In thisreduction to practice the hypertext-type database includes multimediaelectronic documents in the period of American History from 1800 to1850. In the implementation, options or "guides" are utilized whichrepresent prototypical characters from the period of American Historycovered by the database.

As shown in FIG. 5a, which is an actual reproduction of the computerdisplay used in this implementation, the set of guides provided includean Indian, a settler, a minor, a sea captain, an author, a diplomat, anitinerant preacher, an inventor, a slave and a scout. A user can selectone of these ten guides from the screen which depicts them. Once a guideis selected, a smaller iconic representation of that guide appears in abox at the top of the screen, confirming the user's choice.

Referring now to FIG. 5b, a screen display is shown in which a slave hasbeen selected as the guide. The option index terms characterizing thatselected option are displayed, such as ABOLITION, BLACK AMERICANS,SLAVES, etc. Additionally, the guide's recommended first move, to thearticle entitled "Black Americans" is shown. The user can take thissuggested article as a point of entry into the database. Alternatively,the user can re-enter the database anywhere with the chosen guide intow. As the user moves through the information, the guide appears at thebottom of the screen whenever he or she can suggest a relevant nextmove.

Referring now to FIG. 5c, a screen display is shown of the selecteddocument entitled Black Americans. At this point, the user is at aspecific node in the database. The representation of the slave in thedisplay serves as a reminder that the particular guide being utilized isa slave. However, by selecting the representation "Guides" at the bottomof the screen display the user is free to choose a different guide. Thescreen display also shown that the guide's next first choice is thedocument entitled "ABOLITIONISTS".

Referring now to FIG. 5d, a screen display is shown in which the userhas requested not only to be provided the selection of a first choice,but in addition, he is provided a ranked list of choices. The depictionof a slave is shown in the upper right corner of the inserted window toremind the user of the selected option for which linked documents arecompared to in order to determine their relative relevancy. In theparticular implementation described, the aforementioned equation forcomputing match values was utilized. If the match value exceeded thecutoff value of 0.005 an article was included in the ranked list ofarticles for the specific guide.

Referring now to FIG. 5e, yet another display option is shown. Thisdisplay option provides an indication as to the document index termscharacterizing the present document and corresponding option index termscharacterizing the selected option i.e., Slave.

FIG. 5f shows another display illustrating a command option whichprovides information as to why a specific selection on the ranked listof documents would be particularly interesting in view of the selectedoption. Thus, the article entitled GABRIEL'S INSURRECTION is interestingbecause it contains index terms which correspond to option index termscharacterizing the Slave.

Obviously, many modifications and variations of the present inventionare possible in light of the above teachings. It is therefore to beunderstood that, within the scope of the appended claims, the inventionmay be practiced otherwise than as specifically described.

What is claimed and desired to be secured by Letters Patent of theUnited States is:
 1. A method for a user of a computer system totraverse a database to retrieve an electronic document stored in saiddatabase, said method comprising the steps of:a) providing ahypertext-type database, said hypertext-type database including aplurality of hypertext-type nodes, each of said hypertext nodescorresponding to an electronic document, wherein each of saidhypertext-type nodes may be selectively linked to other of saidhypertext-type nodes; b) providing a set of descriptive index terms; c)indexing said hypertext-type database by assigning a unique first subsetof said descriptive index terms to each of said electronic documents; d)providing a plurality of first command options on a computer controldisplay system (CCDS), said CCDS coupled to said hypertext-typedatabase, each first command option representing a second subset of saiddescriptive index terms; e) said user selecting a first command optionon said CCDS; f) comparing said first subset of descriptive index termsof said electronic documents with said second subset of said descriptiveindex terms of said selected first command option; g) producing a rankedlist of electronic documents based on said comparing step f), saidranked list of electronic documents having a highest ranked document,and remaining electronic documents selectively linked to said highestranked document, said highest ranked document representing a user'sposition, within the hypertext-type database; h) providing a pluralityof second command options on said CCDS; i) said user selecting one ofsaid second command options on said CCDS, said one of said secondcommand options representing a desired electronic document in saidranked list; and j) changing said user's position to correspond withsaid desired electronic document corresponding to said one of saidsecond command options.
 2. The method of claim 1 wherein said step ofproducing a ranked list of documents includes assigning a match value toeach electronic document selectively linked to said user's position,said match value being a numerical indication of the relevancy of eachdocument of said ranked list of documents to said second subset of saiddescriptive index terms.
 3. The method of claim 2 wherein said matchvalue is computed according to the following equation:

    MV.sub.d =(i.sub.od).sup.2 /i.sub.o ×i.sub.d

where, MV_(d) =the match value of a document, d; i_(o) =a number ofdocument index terms characterizing said selected first comma option;i_(d) =a number of document index terms characterizing the document forwhich a match value is being determined; and, i_(od) =a number ofco-occurring index terms when comparing the document index terms ofdocument d, for which a match value is being determined and the optionindex terms characterizing that particular option.
 4. The method ofclaim 3 wherein the step of selecting said first command option includesselecting an option which is represented by a portrayed character orpersonality associable to the user as being biased toward a particulartype of information.
 5. A method for retrieval of documents from adatabase, said database comprised of a plurality of electronicdocuments, each of said plurality of electronic documents capable ofbeing selectively linked with other of said electronic documents; saidmethod comprising the steps of:a) defining a set of descriptive indexterms for said plurality of electronic documents; b) indexing saiddatabase by assigning a unique first subset of descriptive index termsto each of said electronic documents; c) providing a plurality of firstcommand options on a computer controlled display system (CCDS) coupledto said database, each of said plurality of first command options havinga unique second subset of said descriptive index terms; d) receiving oneof said first command options; e) comparing said first subset ofdescriptive index terms of said electronic documents with said secondsubset of said descriptive index terms of said received first commandoption; f) generating a first ranked list of said electronic documentsbased on comparisons of step e), said first ranked list including apresent position document; g) providing a plurality of second commandoptions on said CCDS, each of said plurality of said second commandoptions associated with one of said electronic documents on said rankedlist; h) receiving one of said second command options; i) retrievingsaid electronic document associated with said received second commandoption, said retrieved electronic document becoming the present positiondocument.
 6. The method as recited in claim 5 further comprising thestep of generating a second ranked list of documents which contains onlydocuments, that are selectively linked with said retrieved electronicdocument.
 7. The method as recited in claim 5 wherein said step ofgenerating a first ranked list of electronic documents includesassigning a match value to each electronic document, said match valueproviding a numerical indication of the relevancy of said electronicdocument with said received first command option.
 8. The method asrecited in claim 7 wherein each of said match values is computedaccording to the following equation:

    MV.sub.d =(i.sub.od).sup.2 /io×id

where, MV_(d) =a match value of a document, d; i_(o) =a number of optionindex terms of said received first command option; i_(d) =a number ofdocument index terms characterizing the document of which a match valueis being determined; and i_(od) =a number of co-occuring index termswhen comparing the document index terms of said document d, for which amatch value is being determined, and the option index terms of saidreceived first command option.
 9. The method as recited in claim 8wherein said step of providing a plurality of second command options isfurther comprised of selecting only said ranked electronic documentswhich have a match value greater than or equal to a predeterminednumber.
 10. The method as recited in claim 9 wherein said predeterminednumber is approximately 0.005.
 11. The method as recited in claim 5wherein said step of providing a plurality of first command options isfurther comprised of generating, for each first command option, aportrayed character or personality associable to the user as beingbiased toward a particular type of information to cause retrieval of aparticular type of electronic documents.